1. Field of the Invention
The present invention relates generally to a trailer. More particularly the present invention relates to a trailer providing dumping capabilities and having the additional capabilities of raising for level-loading and unloading at loading docks of various heights and lowering for easy loading and unloading at ground level.
2. Background Art
Trailers for hauling machinery and other cargo are commonplace. Many trailers available today provide a dumping feature, mostly for effortless unloading of loose cargo such as gravel, sand, soil, etc.
For loading and unloading machinery, commonly a machine must be driven up and down ramps to load and unload. Some trailers are made to tilt, much like the dumping feature previously mentioned, for loading and unloading. Most commonly, the cargo hauled by these trailers is fairly light, such as snowmobiles.
If a machine or other heavy cargo must be unloaded from a trailer at a loading dock, the elevation of which is much higher than the trailer deck level, significant ingenuity or a serious hoisting operation may need to be exercised to transfer the machine or cargo.
A trailer, made to adjust into a low, loading position is disclosed by Stringer in U.S. Pat. No. 6,273,435. The trailer of this patent is capable of being moved from a first or lowered position to a second or elevated position in a substantially vertical or nontilting manner. Truss-like sides, affixed to the trailer deck, provide channels engaging the trailer's frame. The frame remains at the same level relative to the axle while the deck and truss-like sides raise and lower relative to the axle. This trailer does not have a dumping capability, nor can it be raised to load or unload from a loading dock. The design of this trailer, where the truss-like sides are affixed to the deck, precludes the possibility of raising the deck significantly because the truss-like sides would be required to extend significantly below the deck, and would thus contact the ground.
There is therefore a need for a trailer that dumps, lowers into a loading position, and, raises for loading and unloading from a loading dock or other elevated location. There is a further need for a trailer having a structure for raising and lowering the deck that is rigidly affixed to the frame to which the wheels are affixed.